1. Field of the Invention
The present invention relates to a telescope having a barrier member for protecting an optical system.
2. Description of the Related Art
In general, that are one form of telescopes, have objectives and eyepieces, which are located at the front and back ends of paired lens barrels, exposed externally. When the binoculars are unused (stowed), if they are left intact, dust or oil and fat adhere to the surfaces of the lenses. When the adhering dust is wiped away, the lenses may be damaged. In conventional binoculars, a lens cap serving as an optical system protecting member is provided for groups of objectives and eyepieces in each of the right and left lens barrels.
However, the lens cap is merely mounted on the circumference of each lens barrel. The lens cap therefore readily comes off due to an extraneous force or the like. Moreover, there is a fear that the lens cap may be lost. For preventing the loss, a proposal has been made of binoculars having one end of each lens cap thereof coupled to the body of each lens barrel using a string-like member. However, the binoculars having one end of each lens cap coupled to the body of each lens barrel using the string-like member are hard to handle because the dismounted lens caps swing. Moreover, the appearance of the binoculars having the dismounted lens caps swinging is unfavorable.
Binoculars having a barrier, which can slide, mounted on the front surface of each lens have been proposed in the past. Before the binoculars are used, a barrier handler is manipulated in order to move the barrier. The lenses are thus freed. Thereafter, the lenses are focused and observation is carried out.
However, in the conventional binoculars having the barrier mounted on the surface of each lens, before observation is started, the barriers must be manipulated in order to focus the lenses. The manipulation of the barriers and a manipulation to be performed for focusing are independant and annoy a user. Moreover, since both a mechanism for driving the barriers and a mechanism for focusing the lenses must be included, the structure of the binoculars may become complex.
Accordingly, an object of the present invention is to provide a telescope whose usable state and unused state can be changed by moving a barrier member to a position of withdrawal and a position of protection relative to an optical system. Herein, the barrier member can be readily changed from the position of protection to the position of withdrawal.
According to the present invention, a telescope has a barrel, an optical system moving mechanism, and a barrier member. The lens barrel bears an optical system. The optical system moving mechanism is used to move the optical system between a position of non-use and a position of use. The barrier member can move to a position of protection at which it protects the front surface of the optical system and a position of withdrawal at which it has withdrawn from the front surface of the optical system. The barrier member is moved to the position of protection or the position of withdrawal responsively to a manipulation performed on the optical system moving mechanism. The barrier member can thus readily be changed from one state to the other.
The other features of the present invention and advantages thereof will be fully apparent from the description below.